Process of manufacturing coke



vmen. mm com, or name, commmo', -ASSIGNOR To comrnNmbr new Yoax, N. 2., A CORPORATION or Patented July 18, 1933 UNITED: STATES PATENT OFFICE DELAWARE rnocnss or murac'ruamc con.

ms Drawing.

This invention relates to a process ofmanufacturing coke. More particularly the invention comprises a proces for the production of a metallurgical coke from petroleum or other suitable mineral oils.

In the metallurgical industries the need of a more eflicient and reactive coke has long been apparent. Furthermore any coke hav- I ing these properties must also have suflicient structural stability or compressive strength so that itmay be used in blast furnaces, cupolas or other furnaces where it must sustaina considerable I crushing strain. The metallurgical coke produced from coal contains high percentages of ash and other impurities which contaminate the metal roduct when it is used for reducing or re Various attempts have been made to remove the ash from coal prior'to coking the same in order to producea coke of low ash and high carbon content,'but such processes are very expensive and have not been adopted.

An object of the present invention is the production of a superior metallurgical coke of low ash content and which has a high B.t.u.value.

A further object of the invention is the provision of a process for the production of a coke having a high B. t. u. value and a crushing resistant strength suitable for metallurgical purposes.

In accordance with these objects the invention comprises the heating of petroleum oil under such conditions as' -to convert the oil into a solid intermediate-coke or carbon residue as well as useful "liquid and gaseous products, the intermediate coke or carbonaceous residue being then charged to a coking oven or retort where it is coked for a considerable period of time at a high temperature.

. With these and other objects in view the invention will be best understood from the following detailed description thereof in con-.

nection with certain specific examples.

The oil to be treated, which may be petroleum or other mineral oil, is passed under pressure in a small stream through a heating zone in a substantially continuous stream after which the oil is delivered to a reaction chamber. During its passage through the heatin zone the oil is subjected to a temperature o from 800 to 1000 F. for a sufficient len th of time to bring the oil up to a cracking or ecomposing temperature. As oil from the ing metals.

Application filed July 19, 1928. Serial No. 294,059.

heating zone is discharged into the reaction" chamber it is vaporized to a large extent and the chamber is preferabl large enough to permit a large amount of expansion of the Y vapors. The reaction chamber is preferably highly insulated and valved so that a crackin temperature and pressure will be maintaine therein. The vapors formed in the reaction chamber are delivered to a suitable recti tower and condensing equipment by w 'ch desired liquid products may be recovered, such as gasoline or pressure benzene and a reflux condensate that is preferably removed 1 from the condensing equipment and returned to the oil being charged to the'heater. The oil remaining unvaporized in the reaction chamber continues to undergo a thermal decomposition therein whereby the lighter hydrocarbon products are cracked to form the vapors that pass through the condensing equipment, and a residue consisting prin-. cipally of a semi-coke which remains and builds up until it practically fills the reaction chamber. This semi-coke may carry a greater v or less amount of free oil in accordance with 30 the pressure and temperature maintained in the reaction chamber. At temperatures be tween 700 and 900 F. the ercentage of free oil in the coky' residue may e held below 5%. The temperatures and pressures as well as the time of reaction are carefully controlled in the reaction chamber in order that the coke may be made comparatively soft and friable. This result is obtained to' assist in removing the coke -from the reaction chamber because in the ordinary process of cracking'topped crude oil or fuel oil, or heavy gas oil, a reaction chamber 10 feet in diameter and approximately 40 feet high will fill with semi-- coke in from thirty to forty hours operation.

soon as possible thereafter the coke is removed from the reaction chambers in order to prepare them for another cracking operation; By placing chains, cables and other devices within the reaction chambers, the coke may be broken up into such a condition that it sufliciently m efliciency of f may be readily removed from the reaction chambers. Preferably the nature of the coke is such that it will contain a very high percentage of fines and will be s ightly wetted with oil.- If practical it is deslred to have all of the coke removed from the reaction chambers of a size which will pass through a 4-mesh screen.

The fine coke removed from the reaction chambers is then further treated to make a metallurgical coke. To accomplish this the petroleum coke breeze from the reaction chamber is char ed into a retort or by-product coke oven 0 amber and tightly sealed. The retort of the chamber is then externally heated to a temperature of from 1300 to 1850 F. and substantially all volatilizable material distilled from the coke. The charged coke contains enough cementitious material so that under the temperature within the retort it melts and the volatile material is distilled ofl while in the melted condition. The coke resulting from this heating operation is a fine grained crushand impact-resisting metallurgical coke having a very low ash content and low in volatiles. The coke yield from the semi-coke is higher than that obtained from coal and may vary from to 84% depending on the volatile content of the semi-coke. The heating value of the coke produced usually runs above 14,000 B. t. u. per pound but may vary from 13,600 to 14,300 B. t. u. per pound. During the distillation a gas is formed having a B. t. u. value of from 400 to 500 per cubic foot and a volume of from 6000 to 7000 cubic feet per ton of semi-coke carbonized. A high grade tar is obtained as a by-product by scrubbing the gas as it leaves the coking oven or retort. The yield of tar amounts to about 12 to 16 gallonsper ton of semi-coke.

The final coking of the solid petroleum residue or intermediate coke is preferably carried out in the usual type of beehive or by-product coke oven or other suitable retort where a comparatively large mass of the material is subjected to coking temperatures While maintained in a relatively quiet condition. The time required for coking the material will vary to some extent depending upon the character of the residue but very satisfactory results have been obtained by the use of a coking period of only 6 hours. Longer periods may be used if desired.

As a specific example of the oil treated and the products produced therefrom, reference is made to the following data on the treatment of an asphalt base oil from Wyoming. By subjecting this oil to decomposition in the manner referred to above about 5% of the oil was converted into solid carbon residue which was separated from the residual oil so as to leave the solid material comparatively free of oil. This carbon residue or breeze as charged into the coking oven showed the following properties (dry basis) I In a particular run on petroleum breeze of this character, and in which the coking period was 6 hours, the following quantities of materials charged and products were involved:

Petroleum breeze charged (dry) lbs Total gas (cu. ft.) at 60 F. and

30" of Hg 214, 600 Coke produced (dry) Furnace coke (over 1 screen) lbs 43, 996 Nut coke (through 1% screen over 1;" screen) lbs 1,263 Breeze (through screen) lbs- 4, 364 Total coke produced lbs 49, 623 Coke yield 79% Tar produced (gallons) 432 Tar produced per ton of dry petroleum breeze (gals) 13. 8

The coke produced in the above run had the following characteristics:

Vo atile matter 4. 25% Fixed carbon 94. 70% Ash 1. 05% Sulfur 1. 35% Heating value, B. t. u. per lb 14, 188 Specific gravity (apparent) 957 Specific gravity (true) 1. 499 Porosity 36. 1%

Shatter test: Coke over 1%" clear opening screen 79.5% Coke through 1%" clear opening screen 20.5%

The shatter test consisted of allowing a 50-lb. sample of 1% and over coke to drop four times onto a cast iron plate from a height of 6 ft. The coke was then screened on a 1% clear opening screen and the two portions weighed.

In physical appearance the coke has a dark, grayish and comparativel dull appearance, but shows some lustre on racture. The

Heating valu (average) poresof the coke are comparatively small, relatively uniform in size and welldistributed throughoutithe body of the coke. The coke furthermore, as madefrom the etroleum breeze, clearl shows a thoroug y fused and bonded prodiict having none of the fingery and spongy character of some cokes made from coal.

The gas produced in the coking operation showed the following analysis and other properties:

Analysis:

Carbon dioxide 2.11% Illuminants 2.07%

' Oxygen 1.51% Carbon monoxide 2.12% Hydrogen 55.09% Methane 20.54% Nitrogen 16.56%

Total 100.00%

Calculated from analysis B. t. u. per

cu. ft

. 434 Observed Junker calorimeter B. t. u.

per cu. ft 451 Average of calculated and observed 442 e tar produced in the carbonizing or coking o eration gave the following products on distillation: i Semi-solid (about liquid' car-.

bolic oil) 310 to 464 F 1.5% Gas oil 464 to 518 F Fat (water gas tar) 518 to 554 F 2.5% .Water gas tar fat 554 to 608 F--- 9.0% Water gas tar fat 608 to 650 F- 13.00%

Water gas tar fat and chrycene Specific gravity-::::::::::

650 to 700 F 17.00%

1.22 The pitch. from this tar amounted to 51%,

showed a melting point of 167 F. and a carbon content of 24.27%.

The itch is very ductile and elastic with a. "high ine on fracture.

The present invention is not to be understood-as limited to the use of the particular intermediate coke or carbon residue produced the oil decomposition process described a ove, but it contemplates the use of such materials as are now produced in the various rocesses of cracking petroleum where gasome is the desired product. Various attem ts have been made to utilize the coke resi ue from cracking stills as a fuel but due produced by the present process is especially desirable and adapted for use in reducing relatively pure ores such as bauxite for the production of aluminum and in other cases where the ash content of the coke would contaminate the final product.

In the specific example given above referonce was made to the use of an asphalt base mineral oil but tests have shown that the carbon residue derived from the decomposition of a parafiin base oil coked in a very sim- 1lar manner to that of the asphalt base oil residue. It will readily be understood however that a petroleum coke? produced under certain conditions would not fuse and form a coherent coke like the product of the present invention. For exam le where an oil is directly fired and distilled to dryness the residue produced is a very fragile porous material containing substantially no volatile matter and would have no more coking properties than ordinary coke breeze. This material may be coked however by mixing it with a heavy residuum or fluxoil and treating the same as the semi-coke.

While it is not definitely known what the coking property. of the intermediate or semicoke is, it is believed that the solid carbon particles as formed in the oil during the de-' composition, besides containing free carbon also contains highly polymerized hydrocarbon bodies which give the coking property tothis intermediate coke product. This view is supported by the analysis given above which shows a volatile content for the petroleum breeze about the same as that of some cok coals. p 5 he metallurgical coke produced by the process of the present invention has been compared in certain respects with the regular beehive oven coke and in a particular instance where it was used in a cupola for melting iron it was found that the coke melted approximately 1 lbs. more. iron per lb. of coke than the 72 hour beehive coke produced from Colorado coal. The following comparative tests also show the outstanding superiority of a specific sample of the product of the present invention over the regular 72 hour metallurgical coke 72-hour g g' metallurglee] coke Volatile matter 2. 927 2. 447 Fixed wn 95. 93% 84. mi Ash 1.167 12 057 Sulfur 1. 29% 0. 9s 0 gen. per lb. t) 1 4 32.8354

peclflc 8 pal-en Specific ice: 1. 523 1. 850 g mm w 31.17 ems Thru 1% screen 20. 44% 22. 12% Over 1%" screen 79. 32% 71. 437 o. 24% o. 45%

From the above comparative tests it will be apparent that the special coke which remetallurgical coke has a gneaterresistance to impact and abrasion than the 72-hour coke and at the same time a higher B. t. u. value and lower ash content. Coke made from coal often contains largeparticles of slaty material which tend to weaken the coke. The product of the present invention as produced from any oil contains less than 2% ash and therefore is of a very uniform character in respect to its composition, reactivity and resistance to compression and impact. No instance is known in which a coke produced from coal contained as little ash as the present product.

It is to be understood that the oil to be subjected to the decomposition'process may be either crude petroleum or other crude mineral 011 or a particular fraction thereof, such as gas oil, kerosene or residuum.

Having described the invention in itspreferred form what is claimed as new is:

1. The process of manufacturing a hard thoroughly bonded coke having a high resistance to impact and abrasion from a cokable petroleum coke containing approximately 18% of organic volatile matter, and 0.8% ash, and produced by the cracking of an asphalt-base petroleum oil, which comprises subjecting a substantial mass of said petroleum coke in a coking zone to a coking temperature in the absence of air until the petroleum coke is converted into said hard thoroughly bonded coke having between 2 and 5% organic volatile matter, and adapted to give a shatter'test in which approximately 80% of the coke passes over a 1% inch clear opening screen.

2. The process of manufacturing metallurgical coke, which comprises coking a body of friable cokable petroleum coke containing approximately 18% organic volatile matter produced by cracking an asphalt base petroleum oil in liquid hase, said coking comprising the heating of a stationary body of said petroleum coke in a. loose state in a retort or oven, in the substantial absence of air toa temperature of from 1300 to 1850 F. until the petroleum coke is converted into a coherent metallurgical coke having between 2 and 5% organic volatile matter.

3. The process of manufacturing metallurgical coke, which comprises coking a body of friable cokable petroleum coke produced by cracking an asphalt base petroleum oil in liquid phase, said coking comprising the heating of a stationary body of said petroleum coke in a loose state in the substantial absence of air to a temperature of from 1300 to 1850 F. until the petroleum coke is converted into a coherent metallurgical coke having between 2 and 5% organic volatile matter.

4. The process of manufacturing metallurgical coke, which comprises coking a body of friable cokable petroleum coke containing approximately 18% organic volatile matter produced by cracking an asphaltic petroleum oil, said coking comprising the heating of a stationary body of said petroleum coke in a loose state in a retort or oven in the substantial absence of air until the petroleum coke is converted into a coherent metallurgical coke having between 2 and 5% organic volatile matter.

5. The process of manufacturing metallurgical coke, which comprises coking a body of friable cokable petroleum coke produced by cracking an asphaltic petroleum oil, said coking comprising the heating of a stationary body of said petroleum coke in a loose state in the substantial absence of air until the petroleum coke is converted into a coherent metallurgical coke having between 2 and 5% organic volatile matter.

VIRGIL LEE BOARD. 

